Who is Tianxu Solar
Tianxu is a world-renowned, award-winning, high-tech company, leading designer and manufacturer of solar hot water systems, all-glass evacuated solar collector tube and flat-plate collector, for domestic and business applications.
Our strength comes from our joint share holders, Tianxu Holding Co., Ltd of Tianxu University. This company was founded 25 years ago by Tianxu University Professor Yin Zhiqiang with a specific focus s on the development of Solar Selective Coating on Evacuated Tubes technology.
Tianxu has since grown into one of the most influential company in Chinese solar industry . All of our products are manufactured with a strong emphasis on ease of installation to provide optimum integration of solar water systems into building design, while aiming to minimize the environmental impact of all products and operations. Besides, we attach a particular attention on customer service .
Tianxu solar is at the forefront of most of solar thermal technologies, as we are currently using our expertise to also work on solar space heating, solar cooling , seawater desalination , air source heat pump, computer controlled heating systems and photovoltaic application systems.
Here at Tianxu Solar systems Ltd we are committed to investing technology and manpower to achieve a bright and clean future, and to providing simple and effective solutions for families and businesses concerned about climate change and rising energy costs . What is all-glass heat pipe?
1. Traditional all-glass evacuated tubular solar collector
Chinese traditional all -glass evacuated tubular solar collector (Fig.1) owns the property of using vacuum as insulating material. Vacuum is highly more efficient than any other artificial material that can particularly be found in Western flat collector. Besides, a specific coating selected by our company for its absorbing properties is used to attracts solar energy, then encapsulated by the vacuum. The vacuum environment can last over 15 years.
1 .End of a traditionnal all-glass evacuated tubular solar collecto
2 .End of the collector, focus on the retainer and the getter
3 .Sectional view of a traditionnal all-glass evacuated tubular solar collector
Fig.1 View of the traditional vacuum tube Tianxu Solar Systems Ltd
2. Improved all-glass heat pipe
Improved all -glass heat tube, although widely inspired by traditional all -glass heat tube, still features important distinctions, proving to be highly more efficient and safer.
2.1 Unsealed open end VS condenser tube
The traditional evacuated tubular solar collector is designed with an unsealed open end, directly connected with the inner cylinder of the water storage tank . Then the water circulates between both of them. On the contrary, the improved all -glass heat pipe is designed with a sealed end made of a silicon cover, called condenser tube, functioning as the water storage tank . The main consequence is that there is no water operating in the solar collector.

Fig.3 Tianxu Solar condenser tubes
2.2 Shockproof ring
The shockproof is made of stainless steel and ensures inner tube and outer tube fixed.
2.3 Heat transfer fluid
The heat transfer fluid inside the tube is Tianxu Solar patent material and can operate efficiently even at - 40 ºC in cold weather.
3. Operating principle of the improved all-glass heat pipe
When the high efficiency selective absorbing coating absorbs solar radiation, it converts solar energy into heat energy. The heat transfer fluid owns the property of low boiling point and low freezing point .
The fluid temperature rises through solar energy absorption process, exceeding its boiling temperature. Consequently, it gasifies and moves towards the upper part of the vacuum tub e, until it reaches the condenser silicon cover, connected to the inner cylinder of the water storage tank.
The cold water in the tank's temperature is lower than the heat transfer fluid, so that the gasified heat transfer fluid condenses and turns back into liquid.
It goes down to th e bottom of the tube by gravity, then absorb solar energy again. Meanwhile, the water in the storage tank has been heat through heat exchange process.
This natural circulation gradually heats the water in the tank.

Fig.6 Operating principle of a sola r water heater with all-glass heat pipes Tianxu Solar Systems Ltd
What are the advantages of all -glass heat pipe?
As there is no water operating in the solar tube, the improved all -glass tube solves the problems of freezing, leaking, scaling and cracking which are rampant in traditional solar water heater systems.
1. Anti-freezing
Traditional all -glass evacuated tubular solar collector is operating with water inside the tube. In cold weather especially during winter, water inside the tube can freeze and break the solar collector. It is a big threat to people's personal safety and property. Besides , most solar water heaters cannot work efficiently in winter because of the water freezing problem. While the heat transfer fluid will not freeze even at - 40 ºC in cold weather.
Tianxu Solar all -glass heat pipe solves this problem and has perfect performance in winter.
2. Anti-leaking
Compared to traditional all -glass evacuated tubular solar collector, Tianxu Solar all -glass heat pipe has the advantage of being anti -leaking.
Considering the glass material of the tubular solar collector, it can be broken during extreme weather, as hailstone. In traditional systems, once the solar collector is broken, water in the tank will all flow out, as the solar collectors are directly connected with the tank. Only if the broken solar collector is replaced can the solar water heater continue to service.
This situation will never happen to solar water heater with Tianxu Solar improved all -glass heat pipes. Since the all -glass heat tube end is sealed with a condenser tube, a heat pipe or more breaking in the middle will not drag along a water flowing out from the tank. Besides, the solar water heater can still work normally.
3. Anti-scaling
Water quality is a very important issue during the service of solar water heater. In bad water quality areas, for instance, some areas in the North of China, the concentration of Ca2+ and Mg2+ is too high; scaling situations are common and very serious. For large-scale solar water heating projects without water pretreatment, the normal operation of the system is highly affected and the solar collecting efficiency is getting lower and lower. The piping system is often blocked, too. Scale deposits in the tubes and tank have to be cleaned regularly to maintain the normal service of the system.
The improved all -glass heat pipe solves this problem. Because it is operating without water in the tubes, there will be no scale deposit in the tank. Given that water in the tank is indirectly heated, scale deposit in the tank is greatly decreased, and there will be no influence of scaling in the tank to the solar collecting efficiency.
4 . Comparison with other type of collector
4.1. Comp rison performance / cost Typ e of collector | Performance Coating | Performance collector | Cost/m2 (USD) |
Flat plate | 75-95% | 40-75% | 100-150/ |
Copper heatpipe | 90-95% | 50-75% | 200-25 |
Glass heatpipe | 90-95% | 45-70% | 70-90/ |
Vacuum tube | 86-95% | 45-68% | 50-150/ |
Plastic sheet | 40-60% | 20-40% | 30-50/ |
The performance of the coating represents the ability of the collector to attract the solar radiations and convert them into heat.
The collector performance represents the ability of the collector to maintain this heat inside the tubes.
Glass heat pipe and vacuum tube possess the b est relation performance/ cost. Indeed their costs are divided by two compared to a flat plate collector or a copper heat pipe collector, for a performance equal or almost equal.
Glass heat pipe and vacuum tube are the most competitive collectors on the market.
4.2. Technical specifications Type of collector | Aperture area | Highest temperature | Pressure | Circulation liquid | Anti-frozen (/100) | Anti-corrosion (/100) |
Flat plate | 2m2 | 120°C | 0-6bar | W G | 50 | 80 |
Copper heat pipe | 2m2/ 3m2 | 180°C | 2-6bar | G | 60 | 80 |
Glass heat pipe | 2m2/3m2/4m2 | 150°C | 0-1bar | W G | 70 | 85 |
Vacuum tube | 2m2/3m2/5m2/7m2 | 200°C | 0-6bar | W G | 80 | 85 |
Plastic sheet | 2m2/5m2 | 50°C | 0-2bar | W | 0 | 100 |
W---WATER G - GLYCLO
Glass heat pipe can reach 150°C, not far away from the high performance of copper heat pipe, and can simply be used under a standard pressure of 0 to 1 bar.
Vacuum tube provide the highest performance, with 200°C, under a range of pressure from 0 to 6 bars, allowing them to comply with the European certification requirements.
In addition to that, they both can be used with glycol or water, as their natural anti -frozen performance is astonishing (70% and 80%), far better than flat plates and copper heat pipe. Their natural anti -corrosion properties (85%) overcome all the o ther kinds of collectors as well (excepted of course a plastic sheet collector).
4.3. Maintenance, Installation and Design Type of collector | Design | Installation | Maintenance |
Flat plate | D2 | C2 | E1 |
Copper heat pipe | D2 | C2 | E0 |
Glass heat pipe | D1 | C1 | E0 |
Vacuum tube | D2 | C2 | E0 |
Plastic sheet | D0 | C0 | E-1 |
E- EASY C - COMPLICATION D - DESIGN
Glass heatpipe and vacuum tube are easily designed and installed on any roof, wall or balcony. Maintenance is convenient too, far more than a flat plate collector.
Where can all glass heat apply?
The outstanding characteristics of improved all -glass evacuated heat pipe guarantee wide applications in several areas .
Tianxu Solar has successfully pushed the application of the improved all -glass heat pipe in domestic use and large-scale engineering projects.
Here are some application fields of the all -glass heat pipe:
1. Domestic solar water heater
Based on traditional non-pressure solar water heater and the structure of all -glass heat pipe, Tianxu Solar has successfully designed the JH series solar water and achieved great market share in China.
2. Solar water heating System
Not only can the all -glass heat pipe b e applied for domestic uses, it can also be applied for large scale systems . Tianxu solar has designed on this purpose the SLL series solar collector (manifold with all -glass heat pipes), as we can see the structure in Fig.8.
The all -glass heat pipe collector is normally vertically placed. And the stainless steel manifold is very strong and has the character of anti -corrosion. The collector is a non-pressure system with high reliability, and solar collector arrays can be easily combined from a few square meters system to thousand square meters system.